The present invention relates to the field of sealing members, and more particularly relates to an elastic supporting and sealing member, which is placed between a first and a second member for gas-sealing the gap between them and also for mutually supporting them one from the other.
There is a known type of thermal foaming seal member for gas-sealing the gap between two bodies. Such a thermal foaming seal member is made from, for example, a mixture of vermiculite, ceramic binder, and organic binder. When such a thermal foaming seal member is heated, it foams and expands and then solidifies, and once it has solidified even when the temperature subsequently drops it does not change state or contract significantly. Further, it is quite resistant to heat. It is a known way for sealing a gap between two bodies to introduce such a thermal foaming seal member into the, in between the two bodies, before the thermal foaming seal member has thus been expanded, and then to heat the thermal foaming seal member in place so as to foam and expand it in situ. By doing this, the expansion is limited by the two bodies on either side of the gap, so that the resultant foamed mass of expanded material is closely conformed to the shape of the gap and tightly seals against the edges of the two bodies, thus forming a gas tight seal between the two bodies. Such a gas tight seal is stable even in a high temperature environment.
Further, there is a known way of supporting mutually two bodies one from the other, in which a wire net member is introduced into the gap between the two bodies, so that they are mutually elastically supported. A relevant example of this is the supporting of a solid catalyst body within the tubular outer casing of an automobile exhaust system catalytic converter. Such a monolithic catalyst body is typically quite fragile, and further typically has a substantially different coefficient of thermal expansion from that of the material of which the outer casing of the catalytic converter is made (typically stainless steel or the like), and so it is known and usual for the monolithic catalyst body to be made as a cylinder somewhat smaller than the inner cylindrical hole within the catalytic converter tubular casing, and for a wire net member of approximately the dimensions of the gap between the outer cylindrical surface of the monolithic catalyst body and the inner cylindrical surface of the tubular casing to be introduced thereinto, so as thereby to support the catalyst body elastically from the casing with a certain degree of resilience being available therebetween. Actually, the wire net member is made somewhat thicker than this gap between the catalyst body and the converter casing, so that when it is crammed thereinto a certain amount of resilient force is engendered, so as to provide a good support between the catalyst body and the casing.
In such a case, it is required to seal the cylindrical annular gap between the monolithic catalyst body and the inside of the tubular casing, in order to prevent exhaust gas passing therethrough and bypassing the catalyst body which it is desirable that said exhaust gas should pass through, and it is known and conventional to provide a thermal foaming seal member of the type described above for blocking this gap, inserted into the gap beside the above described wire net member. With such a construction, the exhaust gas is constrained to pass through the monolithic catalyst body, and also the monolithic catalyst body is resiliently and elastically supported within the catalytic converter casing by the frictional contact of the wire net member with the outside of the monolithic catalyst body and the inside of the catalytic converter casing. Thereby the monolithic catalyst body is well protected against vibration and mechanical shock, and also against booming or vibrations within the exhaust pipe.
However, in the conventional structure of this kind the thermal foaming seal member and the supporting wire net member are constructed separately and are inserted separately into the gap between the monolithic catalyst body and the catalytic converter casing, and this requires a good deal of work and trouble to manufacture and assemble these two separate members, and the products become expensive.
Further, the insertion of the thermal foaming seal member and the wire net member into the annular cylindrical gap between the monolithic catalyst body and the catalytic converter casing require a considerable amount of force. Since the thermal foaming seal member in its state before being heated to be foamed and expanded is very brittle, i.e. is very prone to breakage under tension and rubbing, there is a considerable risk of breaking the thermal foaming seal member during its insertion into place, because of the strong frictional force between it and the outer wall of the monolithic catalyst body and between it and the inner wall of the catalytic converter casing. A method that has in the past been adopted to reduce this frictional force is to coat the thermal foaming seal member with a low friction membrane on one or both of its sides, or to vacuum pack it with a low friction membrane, as a preparatory stage, before inserting it into the gap; however, even with such a troublesome expedient the fittability of the thermal foaming seal member is still unsatisfactory. Further, in order to fit the wire net member more easily into the gap without requiring too much deformation and compression thereof, it has been practiced to reduce the unstressed thickness of the wire net member to a value only just larger than the width of the gap; but this of course reduces the pressure that the wire net member exerts on the opposing walls of the monolithic catalyst body and the catalytic converter casing, and thus reduces its effectiveness as an elastic support for the catalyst body.